In order to transfer liquids it is known to use capillary action which is dependent on the cohesive forces within the liquid and the adhesive forces of the liquid to a capillary medium comprising small channels, e.g. pores or spaces between fibers. Such a capillary medium, e.g. a wick, being introduced through an opening into a reservoir, can therefore be used to draw a liquid out of said reservoir passively by means of capillary action only, i.e. without additional sucking. The transferred liquid may be used to distribute chemical substances to the ambient air in order to generate or mask an odour, to evoke a medical or organoleptic effect or to affect insects.
The U.S. Pat. No. 5,114,625 discloses a fragrance dispenser with a liquid reservoir and a wick with a liquid receiving end disposed in the reservoir for drawing liquid therefrom into the wick. A portion of the wick length is exposed to an air flow provided by a fan.
However, the distribution of volatile chemical substances contained in the liquid in the air flow is not sufficiently homogenous when the air flow is brushing over the wick. Further, in most cases dispensing a substance cannot be done without generation of an external air flow in order to evaporate a given amount of liquid per unit time.
The wicks used in prior art dispensing devices are difficult to exchange as they have to be mounted in such a way that the wick is arranged in a defined position relative to the reservoir. This is rendered difficult as wicks are generally soft. Further, the reservoir including the wick has to be tight to prevent spilling of the liquid and uncontrolled evaporation. The same problem arises with a refill for such a device. A refill already including a wick has to be tightly sealed before use, while refill and wick separated from each other have to be such that the wick is easy and clean to insert and the refill is tight before and during use.
It is therefore an object of the invention to provide a unit for the transfer and distribution of a volatile liquid that has a good efficiency in evaporating liquid, is easy and cheap to manufacture and is easily and hygienically insertable into a reservoir, especially the reservoir of a refill.
It is another object of the invention to provide a method of manufacturing such an improved transfer unit.
It is a further object of the invention to provide a refill suited for the use with such a transfer unit.